Summary
Objectives:
To assess the joint effect of smoking and alcohol consumption on laryngeal risk on
tumor subsites.
Methods:
Population-based case-control study in South-West Germany with 257 histologically
confirmed cases (236 males, 21 females), age 37 to 80 years, and 769 population controls
(702 males, 67 females), 1:3 frequency matched by age and sex.
Results:
Half of the tumors (50.6%) were glottic or subglottic, 17.5% were supraglottic. Due
to advanced stage, the subsite of 31.9% of the tumors could not be determined clearly.
There is a strong increase in risk with increasing tobacco consumption with an odds
ratio (OR) of 59.8 (95% confidence interval (CI) 21.3-167.3) for heavy smoking (>80
packyears (py)), all cases combined. In comparison to current smokers, cancer risk
is reduced for ex-smoking (>2 years) OR=0.36, 95% CI 0.24-0.53. The risks were higher
for supraglottic than for glottic and sub-glottic tumors. The effect of alcohol is
not as strong. A significantly increased odds ratio of 2.0, 95% CI (1.0-3.9) results
for 75-100 g ethanol/day only for glottic and subglottic tumors. The OR rises from
2.2, 95% CI (1.1-4.3) for 100-150 g ethanol/day to 4.3, 95% CI (1.4-13.2) for more
than 150 g ethanol/day (all models adjusted for education). The joint effect of smoking
and alcohol results appears sub-multiplicative but super-additive. Almost 90% of the
tumors can be attributed to both factors.
Conclusion:
Contrary to earlier investigations we observed a sub-multiplicative effect of smoking
and alcohol. The risk for persons with both high alcohol and tobacco consumption is
extremely high which indicates the importance of intervention.
Keywords
Case-control studies - laryngeal cancer - tobacco and alcohol consumption - interaction
- population attributable risk
